class_docstr: Represents unevaluated Gradient.
  
  Examples
  ========
  
  >>> from sympy.vector import CoordSys3D, Gradient
  >>> R = CoordSys3D('R')
  >>> s = R.x*R.y*R.z
  >>> Gradient(s)
  Gradient(R.x*R.y*R.z)
code: def __new__(cls, expr):
      expr = sympify(expr)
      obj = Expr.__new__(cls, expr)
      obj._expr = expr
      return obj
  
imports: import collections
  from sympy.core.expr import Expr
  from sympy.core import sympify, S, preorder_traversal
  from sympy.vector.coordsysrect import CoordSys3D
  from sympy.vector.vector import Vector, VectorMul, VectorAdd, Cross, Dot
  from sympy.core.function import Derivative
  from sympy.core.add import Add
  from sympy.core.mul import Mul
label_desc: Use image node_id 1 for calling the Gradient obj's underlying member method code with example usage: obj.__new__(cls, expr) and returns: obj